The invention is directed to a device for signal shaping or regeneration and for detecting reference marks, in which a square-wave signal is formed from a sinusoidal signal with a singularity and the singularity is unambiguously detected.
As is known for evaluation of a sinusoidal signal, this signal must first be transformed into a square-wave signal to simplify evaluation. Such sinusoidal signals occur, for example, as output signals of inductive sensors which sense bodies with different markings which move past these sensors.
In particular, in detecting the position of the crankshaft or camshaft of an internal combustion engine, transmitter disks which are connected with these shafts and have a number of markings are sensed by inductive sensors and the output signal obtained in so doing is evaluated in the control device of the motor vehicle. Before being evaluated, the output signal of the inductive sensor is changed into a square-wave signal. The sinusoidal signal is compared with a threshold value and a change in the flank or edge of the square-wave signal occurs when this threshold value is exceeded. Such an arrangement is known, for example, from DE-OS 31 27 220.
In this known device, it is necessary to change the threshold value as a function of the anticipated signal height, since the height of the output signal of the inductive transmitter depends extensively on the speed at which the markings pass by and a fixed threshold value would therefore cause excessive inaccuracy.